[test] Disable some tests in back-deployment scenarios.
[test] Disable some tests in back-deployment scenarios.

Bugs relating to scalar alignment and grapheme stride caching were
fixed in 5.1, so they shouldn't be tested when back deploying.

rudkx/swift,karwa/swift,rudkx/swift,benlangmuir/swift,devincoughlin/swift,stephentyrone/swift,glessard/swift,gribozavr/swift,sschiau/swift,lorentey/swift,roambotics/swift,hooman/swift,devincoughlin/swift,karwa/swift,harlanhaskins/swift,gregomni/swift,parkera/swift,sschiau/swift,atrick/swift,benlangmuir/swift,parkera/swift,aschwaighofer/swift,aschwaighofer/swift,gregomni/swift,tkremenek/swift,benlangmuir/swift,xwu/swift,benlangmuir/swift,CodaFi/swift,JGiola/swift,xwu/swift,parkera/swift,JGiola/swift,airspeedswift/swift,gribozavr/swift,apple/swift,allevato/swift,stephentyrone/swift,allevato/swift,JGiola/swift,jckarter/swift,gregomni/swift,xwu/swift,xwu/swift,stephentyrone/swift,JGiola/swift,atrick/swift,jckarter/swift,harlanhaskins/swift,jmgc/swift,karwa/swift,airspeedswift/swift,karwa/swift,gribozavr/swift,hooman/swift,gribozavr/swift,harlanhaskins/swift,devincoughlin/swift,xwu/swift,apple/swift,devincoughlin/swift,tkremenek/swift,tkremenek/swift,roambotics/swift,ahoppen/swift,apple/swift,sschiau/swift,airspeedswift/swift,JGiola/swift,airspeedswift/swift,atrick/swift,allevato/swift,aschwaighofer/swift,harlanhaskins/swift,jmgc/swift,nathawes/swift,ahoppen/swift,hooman/swift,karwa/swift,lorentey/swift,glessard/swift,parkera/swift,glessard/swift,karwa/swift,parkera/swift,hooman/swift,karwa/swift,jmgc/swift,nathawes/swift,devincoughlin/swift,apple/swift,airspeedswift/swift,CodaFi/swift,roambotics/swift,CodaFi/swift,aschwaighofer/swift,nathawes/swift,nathawes/swift,allevato/swift,rudkx/swift,hooman/swift,nathawes/swift,CodaFi/swift,rudkx/swift,glessard/swift,apple/swift,glessard/swift,gregomni/swift,parkera/swift,roambotics/swift,gregomni/swift,JGiola/swift,ahoppen/swift,sschiau/swift,benlangmuir/swift,rudkx/swift,tkremenek/swift,devincoughlin/swift,jmgc/swift,nathawes/swift,karwa/swift,aschwaighofer/swift,jckarter/swift,parkera/swift,benlangmuir/swift,sschiau/swift,atrick/swift,atrick/swift,hooman/swift,stephentyrone/swift,ahoppen/swift,harlanhaskins/swift,lorentey/swift,harlanhaskins/swift,lorentey/swift,stephentyrone/swift,airspeedswift/swift,sschiau/swift,jmgc/swift,jckarter/swift,jmgc/swift,sschiau/swift,ahoppen/swift,xwu/swift,stephentyrone/swift,CodaFi/swift,CodaFi/swift,allevato/swift,jckarter/swift,allevato/swift,tkremenek/swift,hooman/swift,tkremenek/swift,tkremenek/swift,devincoughlin/swift,roambotics/swift,gribozavr/swift,rudkx/swift,airspeedswift/swift,parkera/swift,lorentey/swift,devincoughlin/swift,nathawes/swift,apple/swift,lorentey/swift,gribozavr/swift,stephentyrone/swift,harlanhaskins/swift,lorentey/swift,gribozavr/swift,ahoppen/swift,jckarter/swift,atrick/swift,jckarter/swift,aschwaighofer/swift,lorentey/swift,roambotics/swift,gregomni/swift,aschwaighofer/swift,jmgc/swift,allevato/swift,glessard/swift,gribozavr/swift,xwu/swift,sschiau/swift,CodaFi/swift